3. LIPIDS
INTRODUCTION
• lipids are a group of naturally occurring substances characterized by
their insolubility in water and solubility in some organic solvent.
• They occur widely in the plant and animal kingdom in the form of oils
and fats respectively.The basic structure of lipids is comprised of
carbon,hydrogen,oxygen.
• The lipid fat content of food is the major determinant of the energy
density of diets.
• Fats are essential for the human body, comprising about one-sixth of
our body weight.
• They are integral components of cells and tissues throughout the body.
• Vital organs such as the brain, heart, and liver are protected by fat
deposits.
4. LIPID STRUCTURE
Lipids are the polymers of
fatty acids and that
contain a long, non-polar
hydrocarbon chain in
which the tail is
hydrophobic in nature
and with the small polar
head of molecule
carboxyl group or
containing oxygen, which
is hydrophilic in nature.
5. LIPIDS
Lipids are the structural and functional building blocks of the
living cells and they are made up of hydrocarbons with highly
reduced form of carbon.
Or
Lipids are the substances of animal or plant origin and comprise
of (a). fixed oils, (b).fats, (c). waxes and their derivatives.
Examples of Lipid :- Fats, oils,
waxes ,certain vitamins (such
as A, D, E and K), hormones
and most of the call
membrane that is not made
up of protein.
6. LIPIDS Composition
- Lipids encompass all fats and related compounds, derived from the Greek
word "lipos" meaning fat.
- Similar to carbohydrates, lipids contain carbon, hydrogen, and oxygen, with
some containing phosphorus and nitrogen.
- Lipids have fewer oxygen atoms compared to carbohydrates, resulting in
more energy release (about 2.25 times) per gram during oxidation.
- Body fat constitutes 15-20% of body weight in healthy non-obese men and
18-25% in healthy non-obese women.
- Sedentary lifestyles and aging can lead to increased body fat if physical
activity levels decline.
- Lipids are widely distributed in nature and soluble in organic solvents like
ether, chloroform, and benzene.
- Important groups of lipid compounds include fatty acids, fats and oils,
phospholipids, sterols, and lipoproteins.
7. PROPERTIES OF LIPIDS
• Lipids are oily greasy, non-polar molecules, stored in the adipose
tissue of body.
• They are a heterogeneous group of compounds, mainly composed of
hydrocarbon chains.
• They are energy rich organic molecules, which provide energy for
different life processes.
• Insoluble in water but soluble in organic solvents.
• Hydrophobic or amphiphilic compounds.
• Fixed oils and fat float in water since their specific gravity less than
one.
• Produce permanent stain on the paper.
• Fixed oil and fat are nonvolatile and can’t be distilled without their
decomposition.
• They are significant in biological systems as they form a mechanical
barrier dividing a cell from external environment known as the cell
membrane.
8. SOURCES OF LIPIDS
• Found in all living organisms including humans,
plants and animals.
• Lipids exists in tissues in many forms.
• Simple lipids are often part of large aggregates
in storage tissues, such as oil bodies or adipose
tissue.
• In plants lipids are stored in the form of
triglycerides. The most known is jojoba, which
stores its seed lipid as a liquid wax.
• In oilseeds(sunflowers, linseed) the cotyledons
of the embryo are the major sites of lipid
accumulation.
• Endosperm of the bean, coriander or carrot, is
the main site of lipid accumulation.
• In tobacco, both embryo and endosperm
tissues store lipids.
Human tissues containingfats
Jojoba seeds oil
Linseed oil
Sunfloweroil
Coriander seeds oil
-Tobacco plants and
seed-
9. FUNCTIONS & USES OF LIPIDS
• Lipids are important source of metabolic energy (ATP) so they are the most energy
rich of all the nutrients which provide energy for different life processes.
• They form the structural components of the cell membranes.
• They serve as the biological carriers for the absorption of fat soluble vitamins A,D, E
and K.
• Lipids are also act as lubricants for the passage of food.
• Maintenance of temperature.
• In the base of oil injections.
• In edible/food oils.
• In antiseptic preparations(Tea tree oil is often used in diluted form as a topical
antiseptic for minor cuts, wounds, and skin infections).
• In the treatment of rickets.
• In varnishes and paint industries.
• In cosmetics.
• Also possesses antibacterial properties.
12. LIPIDS
Simple Lipids
• Simple Lipids are esters of fatty acids with alcohols.
The hydrolysis of a simple lipid may be expressed as
Simple lipid + H2O hydrolysis fatty acids + alcohol
Simple Lipids can be sub-divided into:
01. Fats and Oil
02. Waxes
13. FATS & OILS
• If a substance is liquid at 15-16.5 C it is called Fixed oil and solid or semisolid
at the above this temperature, it is called Fat. For example lard, fish oil, ghee,
olive oil etc.
• They are made from two kinds of molecules: Glycerol (a type of alcohol) and
various straight chained monocarboxylic acids known as fatty acids. The fatty
acids of natural fats have 4-24C atoms (and any even numbers). These fatty
acids may be saturated, monosaturated, polysaturated or cyclic unsaturated.
• Fats and oils are commonly called triglycerides or triacylglycerol. Fats normally
saturated fatty acid esters and fixed oils mostly composed of unsaturated
fatty acid esters.
14. LIPIDS
Fats and Oil Introduction
Fats and Oils are the major parts of the lipids present in the adipose
tissues of the mammal.
Fats and and oil are the esters of fatty acids and alcohol and on
hydrolysis gives fatty acids and alcohol.
Fats and oil are mainly the glyceryl ester of various fatty acids like
Palamtic,Stearic ,Oleic,Lenoleic and Lenolenic Aicds.These are also
called triglycerides.
15. LIPIDS(FATS)
Fats and Oil
• Esters of fatty acids with glycerol.
• Solid at room temperature.
• Some are liquid at room temperature, and are known as oils.
• Physical state depends upon the nature of fatty acids.
• Fats are rich in saturated fatty acids.
• Oils are rich in unsaturated fatty acids.
• If the hydrolysis of a simple lipid yields three fatty acids and glycerol,
the simple lipid is called a fat or an oil
16. • Fats
• Esters of fatty acids with glycerol.
• Solid at room temperature longer
chains saturated(only C-C)
• eg. animal fat, butter
• Fats are solid triglycerides
• Oil
• Esters of fatty acids with glycerol
• Oil are liquid at room temperature,
and are known as oils.
• Oils are rich in unsaturated
fatty(C=C) acids.
• eg. many vegetable oils, (olive,
sunflower)
• Oils are liquid triglycerides
20. LIPIDS(FATS)
b.Waxes
Esters of fatty acids with (usually long chain) with alcohols other than glycerol. These
alcohols may be aliphatic or alicyclic.Cetyl alcohol is most common found in waxes.
Waxes are used in the preparation of candles, lubricants,cosmetics,ointments,
polishes etc.
21. Properties of Fats & Oils
• Fixed oils are thick, viscous, yellow-colored liquids with a characteristic Odour.
• They are non- volatile and cannot be distilled.
• They do have food value and can be saponified.
• They turn rancid on storage due to free acidity.
• Fixed oils and fats are insoluble in water and ethyl alcohol, but soluble in
organic solvents like chloroform, ether and benzene etc.
• Fats and oils are esters of glycerols and fatty acids. The oils and fats also
contain various quantities such as vitamins, sterols, antioxidants,
phospholipids, pigments and traces of hydrocarbons, and ketones,
responsible for specific odours and flavors of these oils.
• Physiologically, they are emollients and demulcents.
• Fats are mostly obtain from animal sources and solids at room temperature,
oils are mostly obtain from plant sources and liquids at room temperature.
There are notable exceptions, such as cocoa butter, which is a solid vegetable
oil, and cod liver oil, which is a liquid animal fat.
22. Classification of Oils & Fats
An oil that
hardens to a
tough, solid film
after a period of
exposure to air,
contains more
than 50% of
polysaturated
acids, a key
component of oil
paint &
varnishes. For
example, linseed
oil, hemp, walnut
oils etc.
An oil which
partially
hardens when
it exposed to
air and contains
20-50% of
polysaturated
acids. For
example, castor
oil, mustard oil,
sesame oil.
An oil that does
not harden when
it exposed to air
and contains less
than 20% of
polysaturated
acids. And use in
food, skincare
products and to
condition pliable
materials such as
leather boots. For
example, olive
oil, almond oil,
peanut oil etc.
Examples
of fats
include
peanut,
cocoa
butter
and
coconut
oil etc.
Fats – Bone
tallow.
Oils – Cod liver
oil, shark liver
oil and whale oil
etc.
Fats – Lard , mutton-
tallow and butter
suet etc.
Oils – Lard oil, neat
foot oil etc.
